2007 Mercedes-Benz GL450 Q&A

2007 Mercedes-Benz GL450 Question: Weird sound in the cooling system when I turn off the engine

I bought the car a few weeks ago and didn't notice it until a couple of days ago. When I turn off the engine, after a few seconds I hear a "ffffffff" sound. like if it was releasing some kind of pressure. Any one has any idea of what it could be??? Thanks. -
Answer 1
This sounds like it is the airmatic sytem that is releasing air from the air suspension. It's normal. -
Comment 1
Thanks so much for your answer. What a relief :) -